A Review of Potentillo Ternatae — Nardion Strictae Alliance
A classification of the Nardus stricta dominated communities in the Balkan Range is presented. Two associations are identified: Nardetum strictae and Campanulo alpinae — Nardetum strictae nom. nov. The alliance Potentillo ternatae — Nardion strictae is typified and some comments on its distribution range and syntaxonomical affiliation to the higher units are presented. A synopsis is included of all available associations referred to Potentillo ternatae — Nardion strictae.
This study focuses on mesic and xeric grasslands of mostly secondary origin, and that are influenced by human activity. Mesic grasslands are traditionally used for hay-making, and xeric ones for pastures. Over the last 20 years, livestock farming in Bulgaria has significantly declined so that less grass is needed. Many types of grasslands are no longer used and lots of abandoned fields can be found nowadays in Bulgaria. The analyses in this study are based on 868 releves collected on xeric and mesic grasslands according to the methodological approach of Braun- Blanquet. As a result, five alliances within two classes are recognized: the class Festuco-Brometea, represented by three alliances, namely Cirsio-Brachypodion pinnati, Chrysopogono-Danthonion calycinae and Festucion valesiacae, and the class Molinio-Arrhenatheretea, represented by two alliances, namely Arrhenatherion elatioris and Cynosurion cristati. The majority of the managed grasslands are situated in close proximity to settlements. Most of the abandoned areas (30%) are found within Cirsio-Brachypodion alliance. These grasslands are characterized by the highest values of total cover of vegetation. They are located in the most distant and least accessible areas. If use is not resumed, all the abandoned grasslands will be under threat of extinction in the near future. At the same time, many arable lands have been abandoned and turned into grasslands by the processes of secondary succession.
Mantle vegetation includes plant communities dominated mostly by shrubs and occurs in habitats where the typical tree layers meet difficulties to evolve. This study was conducted in three areas of Bulgaria – Western Balkan Range, Western Sredna Gora Mt. and the Fore-Balkan. Numerical classification and ordination were performed by PC-ORD and JUICE software packages. Diagnostic species were determined by calculating the Phi-coefficient. Two associations and one plant community of the Berberidion alliance were recognized – Corno-Ligustretum Horvat ex Trinajstić ---amp--- Z. Pavletić 1991, Pruno spinosae-Ligustretum vulgaris Tüxen 1952 and Elytrigia repens-Crataegus monogyna community. The latter considered as a successional stage of shrub encroachment into the grasslands. Its species composition is very close to that of the ass. Corno-Ligustretum. The species composition of ass. Pruno-Ligustretum represents a mixture of species characteristic for dry and mesic grasslands, fringe and forest vegetation. The Crataego-Prunetea class is still poorly studied in Bulgaria and much more data from all regions in the country have to be collected.
The Alliances Arrhenatherion, Cynosurion and Trifolion Medii in Western Bulgaria - Environmental Gradients and Ecological Limitations
The vegetation of mesic grasslands distributed in the central part of Western Bulgaria is studied. A significant number of 533 relevés were made following the Braun-Blanquet approach. Classification and ordination of the vegetation was performed. The vegetation is classified up to alliance level. The result of the classification are four groups which correspond to the alliances Arrhenatherion elatioris, Cynosurion cristati and Trifolion medii. Within Cynosurion alliance two well distinct subgroups are observed, differing in moisture of the substrate - provisionally called "wet" and "dry" Cynosurion. Ellenberg Indicator Values are used for assessment of ecology of the habitats. The pasture/mowing management of the studied vegetation types is commented.